It is possible to connect your Parameter to a cell in an Excel spreadsheet by entering this string in the Expression field of the Parameter:

(excel ("C:\Temp\Values.xlsx", "Sheet1", "A1") * 0.0254)

The 0.0254 multiplier at the end is for converting meters back into inches since the Parameter table works in the system units of meters.

There is a video demonstrating this setup located here: https://www.youtube.com/watch?v=O2Oqt-f8-Hc